Pedicle screws are one type of implant used for treating spinal injuries and deformities. In one common treatment, pedicle screws are driven into the pedicles of vertebrae above and below the injured vertebra or vertebrae. A rod is attached to the pedicle screws, for example, by clamps or by threading it through slots in the screws. The rod holds the spinal column approximately in its desired alignment, thereby relieving pressure on the injured vertebra or vertebrae and permitting it to heal and regain its natural conformation. One type of pedicle screw is disclosed in U.S. patent application Ser. No. 163,278, filed Mar. 2, 1988, commonly assigned herewith.
As noted, clamps may be used to connect rigidly the part of the pedicle screw protruding from the vertebra to a spinal support rod. Most of the pedicle screw clamps currently known maintain a fixed distance between the pedicle screw and the support rod and many do not permit relative angular adjustment of the screw and support rod. Thus, current clamps do not allow sufficient adjustment to the specific alignment required by each patient's needs.